1. Field of the Invention
The present invention relates to a working apparatus for mass-production of workpieces such as Coriolis motion gears or the like.
2. Description of the Related Art
The workpiece to be machined by the working apparatus according to the present invention will now be described by using a sample of a Coriolis motion gear. By the way, a principle of a speed change gear train using a so-called Coriolis motion gear which performs the Coriolis motion (hereinafter referred to as a Coriolis motion gear device) is conventionally known. With such a Coriolis motion gear device, it is possible to obtain a large speed reduction ratio using only four gears. The Coriolis motion gear device has various advantages. However, for the Coriolis motion gear, it is necessary to make a gear tooth configuration a spherical involute gear form that is difficult to produce in low cost with a high precision. This is not yet practically produced. The present inventor has made it possible to put the Coriolis motion gear into practice by using a gear configuration instead of the spherical involute gear form. The detail of this Coriolis motion gear device is disclosed in Japanese Patent Examined Publication No. Hei 7-56324.
FIG. 5 shows the Coriolis motion gear device disclosed in the above publication. The Coriolis motion gear device has first through fourth gears A.sub.1 to A.sub.4 as the four gears having different gear tooth number. Among these gears, the first gear A.sub.1 is a fixed gear formed integrally with a housing 6. The second gear A.sub.2 and the third gear A.sub.3 are formed on a rotary member 3 supported by an input shaft 1. Also, the fourth gear A.sub.4 is provided on an output shaft 2 and is pivoted by the housing 6. Then, the first, second, third and fourth gears A.sub.1 to A.sub.4 are engaged with each other.
The rotary member 3 is supported by a slant portion 1a having a predetermined angle relative to an axis of the input shaft 1. Also, the input shaft 1 itself is supported rotatably to the housing 6. When the input shaft 1 rotates, the slant portion 1a takes a swing motion. The rotary member 3 pivoted to this takes a swing motion like a spinning top just before stopping. This motion of the rotary member 3 is referred to as the Coriolis motion. Also, by the Coriolis motion of the rotary member 3, the second gear A.sub.2 and the third gear A.sub.3 are caused to engage with the first gear A.sub.1 and the fourth gear A.sub.4, respectively (see FIGS. 6A and 6B). The second gear A.sub.2 rotates relative to the first gear A.sub.1 corresponding to the gear tooth difference from the first gear A.sub.1 per one cycle of the Coriolis motion (i.e., one turn of the input shaft 1). Namely, one stage speed reduction is attained between the first gear A.sub.1 and the second gear A.sub.2. The motion of the second gear A.sub.2 is directly transmitted to the third gear A.sub.3. The same engagement is attained between the third gear A.sub.3 and the fourth gear A.sub.4. Also, one stage speed reduction is attained between the third gear A.sub.3 and the fourth gear A.sub.4. Namely, when the rotational motion of the input shaft 1 is transmitted to the output shaft 2, the two stage speed reduction effect is attained between the first and second gears A.sub.1 and A.sub.2 and the third and fourth gears A.sub.3 and A.sub.4.
Also, when the second gear A.sub.2 and the third gear A.sub.3 are engaged with the first gear A.sub.1 and the fourth gear A.sub.4 while taking the Coriolis motion, the respective engagement surfaces would be slidably moved with the conventionally known involute gear tooth form or spherical involute gear tooth form. This sliding movement generates noises, vibrations and heat to cause the heat sticking. In order to solve this problem, as shown in FIGS. 5 and 7, rollers 4 and inner contact surfaces 5 with the rollers are adopted for teeth of each gear. More specifically, as shown in FIG. 7, the rollers 4 are floatingly supported to the inner contact surfaces 5, with the rollers, formed in the first gear A.sub.1 (fourth gear A.sub.4) to form semi-cylindrical projection teeth. Also, the inner contact surfaces 5 are formed in the second gear A.sub.2 (third gear A.sub.3) to form the semi-circular groove-shaped recess teeth. Then, when the rotary member 3 takes the Coriolis motion in a direction indicated by an arrow B, the second gear A.sub.2 (third gear A.sub.3) is moved in a direction indicated by arrows C to cause the respective recess teeth to engage with the projection teeth. Then, the sliding movement generated between the respective recess and projection teeth is absorbed by the rotation of the rollers 4. (This is partially excerpted from NIKKEI MECHANICAL Oct. 28, 1996 No. 492.) Accordingly, it is unnecessary to set the backlash, and in addition, the pre-pressure is applied to the respective gears to make it possible to perform the engagement with high precision.
Thus, by using the rollers 4 and the inner contact surfaces 5 with the rollers 4 as the tooth shaped, it is possible to form the teeth less expensively and much more easily than the formation of the spherical involute gear. However, in order to form the semi-circular sleeve-shaped inner contact surfaces with a precise pitch and a precise angle with high precision, it is necessary to perform the positioning by manually using a precise jig or the like. This needs a highly skilled worker and is not suitable for the mass-projection.